DNA Promoters of Cancer Identified

DNA repair is compromised at important regions of our genome, according to a University of NSW study of more than 20 million DNA mutations from 1161 tumours across 14 cancer types.

The study, published in Nature (http://tinyurl.com/h96cbv7), found that for many cancer types, especially skin cancers, the number of mutations was particular high in regions of the genome known as “gene promoters”. These DNA sequences control how genes are expressed and therefore determine cell type and function.

The researchers found that the number of DNA mutations are higher in gene promoters because the proteins that bind DNA to control gene expression block a cellular repair system that fixes damaged DNA. This particular system, known as nucleotide excision repair (NER), can only repair damage from UV light.

Lead author Dr Jason Wong of UNSW’s Lowy Cancer Research Centre said the results provide compelling evidence that increased mutations at gene promoter sites are caused by a compromised NER system.

“What this research also tells us is that while the human body is pretty good at repairing itself, there are certain parts of our genome that are poorly repaired when we sustain damage from mutagens such as UV light and cigarette smoke,” he said.

“By actively avoiding these harmful environmental factors, we can minimise the number of mutations occurring in our body that can lead to cancer.”

Internationally, scientists have so far identified only one promoter mutation that definitively contributes to cancer. “Our study highlights the need for further research on the role of gene promoter mutations in cancer development,” Wong said. “This may ultimately help doctors to determine why certain cancers develop, enabling them to diagnose cancer earlier and select more tailored treatment therapies for patients.”